1. Field of the Invention
The present invention relates to a system for determining distribution of individual cell loss among on-off sources, particularly to a system for approximating individual cell loss and determining distribution of individual cell loss among on-off sources.
2. Description of the Prior Art
There is an urgent need for communication networks to effectively support multimedia applications, as human beings become more and more dependent on networks to communicate with others who can be anywhere in the world. Accordingly, there is a tremendous need to develop sophisticated and intelligent networks which can serve and meet users"" demand anytime and anywhere. However, multimedia applications have a wide range of traffic characteristics and quality-of-service (QoS) requirements. Up to now, only conventional ATM networks and IP networks have shown potential for supporting these applications.
A conventional ATM switch can support thousands of connections at the same time. Each of these connections has distinct traffic characteristics and dramatically differing QoS requirements. These switches have the distinct disadvantage that it is very difficult to make sure each of the individual QoS requirements are met. Practically, it is extremely difficult to monitor and measure the QoS each connection obtains from the network.
A system is therefore needed which can project the performance metrics for each individual connection based on the measurement at the switch aggregate level.
By assuming the incoming traffic is conforming to its declared traffic descriptors (i.e., leaky bucket parameters), information such as the peak cell rate (PCR), sustainable cell rate (SCR), and burst tolerance can be collected from each connection. Based on the measurement on cell loss ratio (CLR) at the aggregate level, an estimate for the CLR for each individual connection can be obtained. If the aggregated cell loss at port level are obtained through measurements and it is assumed that all of the sources have conforming traffic characteristics (usually based on leaky buckets parameters), then the individual cell loss for each connection can effectively be determined. This is particularly true if it is assumed that the connections generate heterogeneous on-off traffic with a given peak rate, mean active, and idle periods.
The present invention includes a system for determining cell loss among on-off sources on a network by determining aggregate cell loss of the sources; determining mean rate of each of the sources; determining burstiness of each of the sources; determining average burst length of each of the sources; determining buffer size; and approximating the cell loss ratio of each of the sources based substantially only upon the aggregate cell loss, the mean rate, the burstiness, and the average burst length.
This approximation can be calculated using the formula:       γ    i    =      γ    ⁢                            ∑                      i            =            1                    N                ⁢                  xe2x80x83                ⁢                  r          j                                      ∑                      i            =            1                    N                ⁢                  xe2x80x83                ⁢                              A            j                    ⁢                      r            j                                ⁢          A      i      
where xcex3i is the individual cell loss ratio, xcex3 is the aggregate cell loss ratio, rj is the mean rate, and A is computed from the formula:       A    i    =                                          T            i                    ⁢                      B            i                                                            T            i                          +        B            
where Ti is the average burst length of each of the sources, Bi is the burstiness, and B is the buffer size.